Control device



J. M. BOWMA N CONTROL DEVICE Sept. 22, 1953 Filed June 5. 1951 I N V EN TOR. mm M. 50mm glow; M 9 M f v, w

Patented Sept. 22, 1953 John M. Bowman, .-Philadelphia,;Pa., :asslgnor to .Philco Corporation, Philadelphia,lPa.,-a.corporation of Pennsylvania Application Juneii, 1951; Serial No. 229,899

7 L'Clalims. .l llhe "present invention ,relates to devices ,for ,controlling the .electron :beam in cathode-ray tubes. Particularly, the inventionlhas to d'owith .a device iof the general kind disclosed in the .Loughren Patent No. 2,525,919, dated October 1'7, .1950, which device employs permanent magnets .totestablish the position of the beam of electrons one-the fluorescent screen of a cathoderay tube. Ina deviceof the above mentioned variety, the

[permanent magnets take the form of magnetized .ringswhieh are disposed concentricallyabout the neck. portionof the tube so as to establish amagneticfield generally transverse to the path of the-electron beam. The rings are arranged for rotation with respect to-each other, as well .as

with respect to the neck .of the tube, to .provide :fonadjustmentof the strength anddirection of the magnetic field -to influence the directional now of electrons and, thus, to efiectcentering .of

the'beamion the screen. Difficulties have herel tofore been encountered in providing suitable simplified means which, not only effectively mounts and adequately supports the magnet ringsjbut also affords sufllcient freedom .to'permit rotational adjustment of such :rings. For example, in an effort to simplify the device, it hasibeen proposed to eliminate the-cumbersome housing. and operating gear structures usedin the prioroart, .and to substitute simple'rotatable disklike I membersprovided with embossed portions which receive themagnetrings to anchor them to said .members vv for rotation therewith. :However, the use of disk-like members whichhave ring engaging embossed .portions is apt to bring about -operational troublesbecause, should :such members become warped or otherwise :accidentally distorted, the magnets. are I likelyto :leave the embossed-portions and hem longer controllable by rotation .of said: members.

It is an important object of the invention to provide an electron beam positioning or centering device of :simplifiedand inexpensiveieonstruction which obviates the aforesaiddifiiculties and operational troubles.

Other andomore v. specific objects of the invention'have toldo with the-provision of a'beamxcentering device whichrequires no complicated parts and which makeitpossible toconstruct the parts from inexpensive readily available materials.

According to a broader aspect of the'invention, the novel centering .device includes a mounting panel on vwhir'zhniagnet rings.arerotatably'supported by vTmeans of a supporting-insulating structure. 'I he .rings are #supported ,1 in such a fashionlthattheycan beselectively rotated either individually aor jointly. The panel, vrings and supporting-insulating structure .constitutea .uni- .ta'ry assembly which is adapted to encircle the neck portion 7 of the tube without. contacting said portion. In accordance .with .a .narrower aspect of the invention, the ring supporting structure comprises a tubular nonemagneticcore on which the-rings are rotatably fitted,-with an insulating .annular spacer between the rings. .Eachringis positively rotated by means of a manipulating tab which isrigidly secured in fixed position on the ring. An important and significant advantage of the above stated arrangement, .is that the position of angular adjustment of the rings, is-assured and. can-always be-visuallylascertained, becausetheconnection between themanipulating .tabs and therings is:such:-that said tabsand rings are .preventedfrom becoming accidentally disassociated.

The .novel .features of the invention and the manner in which the: above recited and other objects and advantages arebest. achieved will clearly appear from .the following description .of the embodiment shown in the. accompanying drawing, in which:

Figure lisa side elevational viewofacathoderay tube of conventional \design and provided with an electron beam centering device construct- .ed in accordance with the invention;

:Figure. 2 is an enlarged elevational viewof .one face of the centering device;

Figure 3 isavertical sectional view taken generallyalong line .l3- 3 of .Figure 2, a ,portion of the neck of the tube being diagrammatically shown to illustrate themelationship .of the .centering device and said neck, portion;

i'FigureA is; a greatlyrenlarged fragmentary perspective view of a section of a .magnetring with its manipulating tab afiixedthereto; (and Figure 1.5 isian exploded -.view, in perspective and on a reduced r scale, Iillustrating the .various parts which comprise the centering Idevice.

With more particular .reference to the drawring, the conventional cathodeeray tube shown in Figure. 1,. includes a tube envelope" having an.enlargedibulbous, portion 10 and an elongatedneck portionil l. The bulbous. portion is providedwith a'fiattened'face |2,'the internal surface of which is coated with a fluorescent substance forming a luminescent screen, .in the .usual manner. The neckportion is provided .with ..a'base ll3 which supports terminals l4 leading to .the gun structure (not-shown) enclosed within said neckportion. Asis-.customary,;a beam .deflecting and focusingzunit l.51.is supported about theneckportion of the cathode-ray tube at a point adjacent the bulbous portion of said tube. The deflectingfocusing unit is supported by means of a bracket ES.

As seen in Figure l, the bracket l6 also serves, in accordance with the invention, to support the novel beam centering device which is generally designated at IT. lhis centering device comprises a mounting panel I8 of suitable non-ma netic stiff material, such as composition or plastic board. As best seen in Figures 2 and 5, the mounting panel is provided with spaced apertures l9 disposed adjacent the marginal edge of said panel. These apertures, as is illustrated in Figure 1, receive bolts 26, or other like suitable fastening elements, to connect the mounting panel with the mounting bracket of the deflecting-focusing unit. In practice, tubular sleeves 2% of predetermined length are interposed between said bracket and panel to locate the latter in proper position with respect to the electron gun within the neck portion of the oathode-ray tube. As more clearly appears in Figures 3 and 5, the mounting panel is further provided with agenerally circular opening 22 which is disposed substantially centrally of said panel.

A generally tubular core 23 of non-magnetic material, such as impregnated cardboard, passes through the mentioned opening of the mount ing panel and serves to support permanent magnets 25, each of which has the form of a magnetized ring which is open or split as at 25 (see Figures 4 and As more clearly shown in Figure 3, these rings are received on said core and fitted for rotation thereon. One end of the core is formed with a flange which abuts one face of the mounting panel and thus prevents said core from passing completely through the opening in said panel. The magnet rings are received on that portion of the core which projects from the other face of the mounting panel, so that the innermost ring abuts said other face of the panel. Retention of the magnet rings on the core is conveniently accomplished by rolling-up the projected end portion of the core, as is shown at 21, and a generally annular band 23 of nonmagnetic material, such as impregnated cardboard, is advantageously used between said rolled-up portion and the outermost magnetic ring to assi t in said retention. Also, a generally annular spacer 29 of non-magnetic material similar to that of band 28, fits over the core and is placed between the magnetic rings to insulate them from. each other.

In particular accordance with the invention,

manipulating tabs 30 are rigidly aflixed to the split magnet rings 24 and extend therefrom so as to be readily grasped to impart rotational motion to said rings about their supporting core. The manipulating tabs are conveniently constructed from strips such as the one illustrated at 38a in Figure 5. These strips are made of insulating material, such as impregnated cardboard, and, as more clearly seen in Figure 4, each strip is folded and clamped in folded position by means of rivets 3|, or like fastening elements, to provide spaced looped portions 32 which encircle the ring adjacent its open or split portion. Further, in accordance with the invention and as is also clearly seen in Figure 4, each manipulating tab is formed to provide a projection or finger 32 which is disposed between and projects transversely of said loops to extend between the confrontin ends of said ring at said open or split portion. The finger on each manipulating tab has a three-fold purpose: Firstly, it prevents accidental closing of the opened portion of the associated ring; secondly, it looks the tabs in position with respect to the associated ring; and, thirdly, it provides adequate visual indication of the relative position of the rings on the supporting structure. It will be understood that the mentioned finger and relieved or split portions elfectually provide the folded or looped strip and the encircled portion of the ring with interengaged keying means which looks the tab forming strip in position with respect to the ring.

The simplicity with which the parts of the device can be assembled is apparent from Figure 5. From this figure, it can be seen that the strips which form the manipulating tabs 39 can be readily secured to the magnetic rings 24; that the core 23 can be readily inserted into the central opening 22 of the mounting panel l8; that said rings, with the interposed annular spacer 29 and annular end-band 28, can be readily slipped onto the core; and that, thereafter, the projected end portion of the core can be readily rolled-up to lock the parts in the unitary assembly shown in Figures 1, 2 and 3. This assembly, as appears in Figure 1, can then be readily slipped over the neck ortion of the cathode-ray tube and secured in position by attachment to the mounting bracket i6 of the deflecting-focusing unit i5, through the agency of the sleeves 2| and the bolts 29. It will be noted that, as clearly shown in Figures 2 and 5, the mounting panel i3 is provided with cut-out portions 33. These cut-out portions are located to register with and to give access to adjusting means 34 (see Figure 1) with which the deflectingfocusing unit is usually supplied. The connection of the mounting panel to the mounting bracket is such that the core and supported magnet rings are disposed in generally concentric relationship with respect to the neck portion of the cathoderay tube, the core bein slightly spaced from the surface of said neck portion (see Figure 3). When using the device, the esircd centering of the electron beam is adequately obtained by rotating the magnet rings to that position which brings about the correct direction and intensity of the centering magnetic field established by said rings. The manner in which the adjustment of the ring acts on the electron beam to position it on the screen of the cathode-ray tube is well known in the art and, accordingly, needs no explanation.

From the foregoing description, it will be appreciated that the present invention provides a simple yet effective device for centering the electron beam on the fluorescent screen area of a cathode-ray tube. The fact that the centering device, in accordance with the invention, includes a mounting panel as one of its parts, is a significant feature because it makes it possible to mount and support the device in correct position without means in direct contact with the neck portion of the tube. Also, the novel mode of associating the magnet rings with the manipulating means employed to position said rings, constitutes a singularly important feature in that it insures proper engagement of said rings with said means.

I claim:

1. A control device for positioning the electron beam on the screen of a cathode-ray tube, comprising a mounting structure, magnetized split rings rotatably retained on said structure, each ring having manipulating means including spaced clamping portions and a projection therebetween, said clamping portions being looped about the ring adjacent its split, and said projection extending into said split.

2. A control device for positioning the electron beam on the screen of a cathode-ray tube, comprising a mounting panel, a core mounted on said panel, magnetized split rings rotatably retained on said core, and manipulating tabs attached to said rings adjacent the split thereof, each tab having a portion projected into the split of the associated ring.

3. A control device for positioning the electron beam on the screen of a cathode-ray tube, comprising a mounting panel having an opening therethrough, a core received in said opening and having a portion extended beyond one face of said panel, magnetized rings rotatably retained on said extended portion of the core, said rings being insulated from each other and having an open portion, and manipulating tabs associated with said rings, each tab being disposed at the open portion of its associated ring and having a finger projecting between the confronting ends of the associated ring at'its open portion.

4. A rotatably adjustable magnet structure for a device adapted to position the electron beam on the screen of a cathode-ray tube, comprising a split magnet ring, and manipulating means carried by said ring and including spaced looped portions encircling the end portions of said ring adjacent its split, said means further including a projection extending between and transversely of said looped portions and between said end portions of the ring,

5. A rotatably adjustable magnet structure for a device adapted to position the electron beam of a cathode-ray tube, comprising a split magnet ring, and a manipulating tab of non-magnetic material engaging said ring adjacent its split and having a portion extended into said split and locking the tab in position with respect to the ring.

6. A rotatably adjustable magnet structure for a device adapted to position the electron beam of a cathode-ray tube, comprising a split magnet ring, and manipulating means for imparting rotational motion to said ring, said means consisting of a strip of non-magnetic material folded over said ring and fixed in folded position to engage the latter adjacent its split, said strip being formed to provide a finger extending into said split.

7. A control device for positioning the electron beam of a cathode ray tube, comprising mounting means including a core adapted to encircle the neck portion of a cathode ray tube, a magnet ring rotatably carried by said core, and manipulating means for imparting rotational motion to said ring about said core, said means consisting of a strip-like tab having a portion disposed in engagement with a portion of said ring, said tab portion and said ring portion having interengaged keying means efiecting an interlocking connection between said ring and tab.

JOHN M. BOWMAN.

References Cited in the file of this patent I UNITED STATES PATENTS Number Name Date 7 2,513,929 Gethmann July 4, 1950 2,544,898 Obszarny et a1 Mar. 13, 1951 2,552,342 Mucher May 8, 1951 2,569,327 Obert Sept. 25, 1951 

